Researchers found that the reduction in breast cancer risk was statistically comparable despite menopausal status, age at migraine diagnosis, use of prescription migraine medications or whether the women avoided known migraine “triggers” such as alcohol consumption, smoking or taking hormone replacements. Such triggers are also well known factors for breast cancer risk.

Important Points

“From an epidemiological perspective, having a larger and more diverse study in its underlying population helps in replicating the finding,” said lead researcher Dr. Christopher I. Li, a breast-cancer epidemiologist at Hutchinson Center’s Public Health Sciences Division. Important differences between this study and the initial one that discovered the link are:

• Sample size was more than four times larger this time. More than 4,500 cases and controls as opposed to about 1,000 each in the first study. The sample population was also more geographically diverse, with women from five urban areas instead of only one.

• Age range of women studied was wider this time, 34-64 years of age versus 55-74 years old. “We were able to look at whether this association was seen among both pre-menopausal and post menopausal women,” Li said. “In breast cancer this is relevant because there are certain risk factors that are different between older and younger women. In this study we saw the same reduction in breast cancer risk associated with a migraine history regardless of age.”

• Researchers were able to determine whether women in the study had lifestyle behaviors which are known migraine triggers. Researchers wondered whether maybe women who had migraines drank and smoked less and didn’t take hormone replacements. “But in this study we looked at women who never drank, never smoked and who also didn’t use hormones and found the same association within each of those groups, suggesting that the association between migraine and reduced breast cancer risk may be independent of those other factors and may stand alone as a protective factor,” said Li.

Still to be made clear is just how migraine bestows its evident protection against breast cancer. “We know that migraine is definitely related to hormones and that’s why we started looking at this in the first place,” Li said. “We have different ideas about what may be going on but it’s unclear exactly what the biological mechanisms are.”

Research Continuing

Currently, research on migraines and breast cancer continues. Li and colleagues are doing a follow-up among women in the first study to establish the timing, types, intensity and severity of their migraines with the idea that the data may elicit additional hints.

The same research group also has submitted a third study for publication finding that the association between migraine and reduced breast cancer risk is maintained regardless of whether women with migraine took non-steroidal anti-inflammatory drugs such as aspirin and ibuprofen. Earlier studies also linked these medications to reduced breast cancer risk.